Carabid beetle description

A large, colourful beetle, Carabus olympiae is unusual in being endemic to just one small area of the Italian Alps (2). As in other ground beetles (Carabidae), the body is rather long and flattened, with a clearly differentiated head, thorax and abdomen, long, slender legs, and quite prominent mandibles and palps(3)(4).

Although not as spectacularly coloured as some of its relatives, Carabus olympiae is still an attractive insect, with a dark purplish-blue head and pronotum, the margins of which have a golden sheen, and brilliant, metallic, golden-green elytra, with coppery or purple margins (2).

Related species

Carabid beetle biology

Most active at night (2)(5), particularly during periods of thunderstorms and high humidity (2), Carabus olympiae is a voracious predator. Both adults and larvae actively hunt for invertebrate prey, and are thought to have a preference for molluscs, in particular the snail Arianta arbustorum(2)(3)(4).

The main period of activity of Carabus olympiae runs from June to September (2), peaking in July (5), with the eggs laid in late spring or early summer. The number of eggs is relatively low, with each female laying a maximum of around 29. The larvae of Carabus olympiae pass through three developmental stages before pupating, with total development taking approximately one to one and a half months. The young adults emerge at the end of the summer and feed for about a month, building up fat reserves before entering diapause during the winter (2)(4). Eggs laid late in the year may pass the winter as larvae, and it is possible that some individuals of this species may delay reproduction if conditions are unfavourable, or even reproduce in more than one successive year (2).

Carabid beetle range

Carabus olympiae is endemic to a small area of the upper Val Sessera, on the northern slope of the Moncerchio, in the Italian Alps (1)(2). Attempts to introduce the species to parts of the French Alps are thought to have been largely unsuccessful (2).

Species with a similar range

Carabid beetle habitat

Believed to have originally been a forest-dweller, Carabus olympiae now occurs in more open habitats, ranging from beech forest to open shrubland, at elevations of around 800 to 2,000 metres (2). It may have a preference for beech forest as well as areas of alpen rose (Rhododendron ferrugineum) and bilberry (Vaccinium myrtillus) (2)(5)(6), but avoids pastures (5).

Carabid beetle status

Carabid beetle threats

Although the very restricted range of this species is believed to have resulted from natural processes occurring after the last ice age, its limited distribution makes Carabus olympiae particularly vulnerable to extinction. The population also fluctuates widely from year to year, and is generally much lower than in related, more widespread species (2).

The main threat to Carabus olympiae is tourist development, in particular for the skiing industry, with the construction of ski runs and pistes severely altering the habitat, and associated roads and traffic also causing damage (2)(5)(7). Potential plans for a hydroelectric dam and for the construction of an artificial lake to feed snow-cannons have also further threatened the area (2).

In addition, activities such as cattle grazing may alter the density of shrubs, potentially affecting Carabus olympiae(6), and the removal of old and dead trees as part of forest management may remove important habitat for the larvae of this and other beetle species (2).

Carabid beetle conservation

Carabus olympiae is listed on Annex II of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention) (8), and as a priority species on Annexes II and IV of the EC Habitats Directive (9). Although efforts have been made to extend the range of the species by introducing it to parts of the French Alps, these do not appear to have been successful (2).

Conservation measures needed for this rare and unique beetle include better protection for the sites where it occurs, and further surveys to determine whether small populations exist in any other areas (2). It will also be important to properly manage the habitat of Carabus olympiae, in particular by managing the availability of shrub cover, controlling grazing pressure, and developing more environmentally friendly ways of constructing ski pistes (5)(6)(7).

Find out more

Council of Europe. (1996) Background Information on Invertebrates of the Habitats Directive and the Bern Convention. Part 1 - Crustacea, Coleoptera and Lepidoptera. Council of Europe Publishing, Strasbourg.

Authentication

Glossary

Diapause

In insects, a temporary pause in development and growth with a definite physiological basis. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.

Elytra

In beetles and earwigs, the hard forewings. They are held aloft when the insect flies, and are often coloured or patterned.

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Mandibles

The pair of mouthparts most commonly used for seizing and cutting food, common to the centipedes, millipedes and insects.

Molluscs

A diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.

Palps

In invertebrates (such as insects, spiders and crustaceans), palps are sensory appendages located near the mouth.

Pronotum

In insects, the hardened cuticle on the upper surface of the first thoracic segment (the part of the body nearest the head).

Pupate

The process of forming a pupa, the stage in an insect’s development when huge changes occur that reorganise the larval form into the adult form.

Thorax

Part of the body located near the head in animals. In insects, the three segments between the head and the abdomen, each of which has a pair of legs. In vertebrates the thorax contains the heart and the lungs.

References

Council of Europe. (1996) Background Information on Invertebrates of the Habitats Directive and the Bern Convention. Part 1 - Crustacea, Coleoptera and Lepidoptera. Council of Europe Publishing, Strasbourg.

Negro, M., Isaia, M., Palestrini, C. and Rolando, A. (2009) The impact of forest ski-pistes on diversity of ground-dwelling arthropods and small mammals in the Alps. Biodiversity and Conservation, 18: 2799-2821.

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